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A/C Conversion R12 to R134A

Discussion in 'The Garage' started by Indyblazer, Jun 12, 2005.

  1. Indyblazer

    Indyblazer Registered Member

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    What parts MUST be replaced to do it right? Any sources on the Internet to help me ? I have a 1984 K5
     
  2. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    If the system is working why would you want to convert? if it is not functioning than most likely you have a blown compressor? In that case you will need a NEW, not rebuilt, compressor, accumulator dryer, orifice tube, and oil. 8 oz. of oil will fill the system and distribute it througout the system, not dump it all into the pump.

    If the system is functional than I would just get all the R12 recovered and recharge it with R134. All that crap about needing a new pump, oil, yada yada...is BS. Just recharge it with 2.75lbs of R134 and call it good.
     
  3. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    and flush the system... make sure you use Ester oil. PAG is for vehicles that have only had R134a for their life because PAG and mineral oil ahould not mix.
     
  4. Blue85

    Blue85 Troll Premium Member

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    There are a lot of things to check for before replacing the compressor. If the system doesn't work, the most likely culprit is that there is a leak somewhere and all of the refrigerant has escaped. As for converting, there are two ways, the good and the cheap.

    The cheap way is to replace nothing except anything that is currently leaking and do a "retrofit kit". These include an oil additive that is "supposed" to prevent bad things from happening due to mixing the oils. These kits usually work, but there are some cases of the whole system failing later on.

    The good way is to flush the entire system and replace the receiver/dryer, orifice tube and pressure switch, while adding a high-pressure cut-off switch. I think the high-pressure switch is required by law in some areas.

    If you want more performance to compensate for the change of refrigerant, you can use the VOV orifice tube or add auxillary condensor fan(s) (or high-flow electric fans instead of the mechanical one). Some people report success from a heater core bypass as well.
     
  5. 4xcrazy

    4xcrazy 3/4 ton status

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    I know everybody says their current (r-12) condensor is big enough for the job, but if you take a close look at them, they ARE different, i am personally going to change out the condensor with a 134a unit, replace the rec/drier, the valve, (forgot the correct name right off for it) and filler-up with 134 and see how she does, will let ya know when i get it done.

    Probably by next Tuesday or so due to funding problems. :frown1:

    The reason i mention the condensor, is because there is a reason a vehicle equipped from the factory, with all 134a components, has a very cool system.

    I have had nothing but problems with my r-12 to 134a conversion as mentioned before, the cheap way, yeah, it runs real cool when driving down the freeway, or have a direct driven fan (no fan clutch) pulling air through the radiator and condensor, but REALLY warms up when in city traffic when the air flow falls. This tells me that SOMETHING, is not getting cooled down enough, to me that would be the freon through the condensor.

    Anyhoo, like i said, i'll post back up on how it works next week when i get the new parts.
     
  6. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    If it is just a leak than yes, he just needs to replace what is leaking. I've found that most of the time when a part has failed, not just a leak, it's the compressor.

    4xcrazy,

    You are correct that a 134 condensor is larger and gives the 134 the extra room it needs to do the same thing R12 can in a smaller area. You should feel a difference with the 134 condensor. I filled up with 134 and use the stock condensor but since I have dual 13.5" electric fans equipped with an A/C relay, it gets plenty cold for me.
     
  7. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    You can actually buy small channel condensors made to work better with R134 that you can fit into your truck. Also, don't fill with same amount of r12 it came with originally. Use just a little less since pressures are higher.

    There are no valves in these trucks on the A/C. The only one? Suburbans with rear A/C have expansion valves.

    These R4 disk compressors on the newer trucks 100% blow with R134, but you can't do anything to change the type unless you change your engine brackets.

    You also may have a direct drive fun, but that also tells me it's a flex-fan. Get rid of it, they SUCK! (Not in a good way for a fan) Replace with stock type fan and a good, new clutch and it will work better.
     

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